I can't get into the Line6 website for some reason either, but if you have the Line6 version it's license is tied to the hardware (i.e. the GuitarPort). You should be able to download the Mac version and it should work fine, but you'll need to get it from the Line6 site...at least that's how I understand it!

If you have the standard version it would be tied to your sonoma key, what you use to log into the Sonoma store.